The present invention relates to a microwave oven and, more particularly, to a microwave oven including a control circuit responsive to an output signal derived from a gas sensor disposed in an exhaustion gas path of the microwave oven.
Recently, a gas sensor output controlled microwave oven has been developed, wherein the microwave generation is terminated when a gas sensor output reaches a preselected level. A typical control circuit is described in copending application, "COOKING UTENSIL CONTROLLED BY GAS SENSOR OUTPUT", Ser. No. 71,179, filed on Aug. 31, 1979 by Takeshi Tanabe and assigned to the same assignee as the present application.
In such a gas sensor output controlled microwave oven, a stable operation of the gas sensor is strictly required to ensure a stable operation of the microwave cooking. However, there is a possibility that a warming heater included in the gas sensor is disconnected while the microwave cooking operation is performed.
Accordingly, an object of the present invention is to provide a gas sensor output controlled microwave oven of a stable operation.
Another object of the present invention is to provide a detection system for detecting an abnormal condition of a gas sensor included in a microwave oven.
Still another object of the present invention is to provide a control circuit for automatically terminating the microwave generation when an abnormal condition is detected in a gas sensor included in a microwave oven.
Other objects and further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. It should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
To achieve the above objects, pursuant to an embodiment of the present invention, a level detection system is provided for detecting an abnormal level of an output signal derived from a gas sensor disposed in a microwave oven. When an abnormal output level of the gas sensor is detected, the microwave generation is automatically terminated and an alarm display is achieved.